1. Field of the Invention
The present invention relates to a data input/output technology, and more particularly to a technology for encrypting data to be secured and inputting/outputting the same between a storage device and a host device.
2. Description of the Related Art
Recently, storage cells have shown significant advances in miniaturization, integration, and mass production, thereby allowing recording media of smaller sizes, larger capacities, and lower prices. Under the circumstances, the inventors have aimed to achieve recording media of yet higher convenience, and contemplated the configuration that a large-capacity hard disk, which has heretofore been connected fixedly to a single host device in typical uses, is rendered detachable from host devices so that it can be handled as a removable medium capable of sharing data between a plurality of host devices. It is highly advantageous if a hard disk of small size, large capacity, and relative high access speed can be used as a removable medium.
For example, see Japanese Patent Laid-Open Publication No. 2000-173158 (its entirety incorporated herein by reference).
In terms of user convenience, this removable hard disk is desirably rendered readable/writable from any host device. Nevertheless, being readable/writable from any host device can also mean the risk of data leak to third parties. Distribution of digital contents such as music and pictures is attracting attention at present. It is thus of importance to develop a technology which can protect data to be secured appropriately, for the sake of adequate copyright protection and the prevention of digital contents leakage.